25600 on a 5D2? who ever shoots at that? being better than that isnt saying alot 25600 is completely unuseable IMO. 6400 is pretty much my absolute limit on the 5d2 with 3200 as the useable limit. As for the 1Dx id be more interested to know which iso values resemble 6400 and 3200 on the 5d2 so i can accurately gauge the real world benefit in number of stops you will gain.
In your perfect world of absolutely clean shots, 51k on a 1DX comfortably matches 6400 on a 5D2. It may even improve upon it slightly.
Whilst i apologise for assuming my comment was worth any merit, it would be wise for you to remember that not all photographers work only in an ideal environment, many us have to take what opportunities we're given and work with them.
Some of us even enjoy pushing our kit to the very limit to see what it is capable of, and see if this gives us a photographic opportunity that would be missed by never going above 800 iso.
My trouble is, i come from an environment where i loaded 3200asa into an A1 then pushed it to 12800 and walked around railway yards at 3am to get hand held pictures at 1/60th with a 50mm f1.8, pictures which are of places that no longer exist. Pictures of people doing jobs and tasks that are no longer done. Yep, they're grainy - but at least they exist- where are the other pictures of those yards, those people, those practices? But best of all, the grain actually gives them some character - as opposed to some of the sterile shots i can get at 25600 with a 5D2.
Oh, and happy new year
LOL ok I just cant wait to see some real untouched raw files at all ISO then i'll make up my mind what suits me and my perfect world or i could by a 1Dx to impress people on the internet and shoot everything at 204 billion iso and 14fps... ok that was a bit flipant.
Regardless a 4 stop real imporvement in ISO is pretty damn good
On a side note why is every sinlge review (almost) on youtube most interested in the burst rate only? seriously 10fps is fine I cant see 14 FPS helping in do much other than burn your shutter out quicker. probably serious sports shooters are the only people that might get a hard on over that.
I would love to see some more thorough reviews.
this one is particularly retarded if you can call it a review
the guy is on a serious youtube campaign to get canon to give him a free camera and lots of lenses
edit: LOL this guy is super lame